EP1937011B1 - Method and arrangement for dynamic management of sub-sectors in a cellular communication system - Google Patents

Method and arrangement for dynamic management of sub-sectors in a cellular communication system Download PDF

Info

Publication number
EP1937011B1
EP1937011B1 EP07024609.5A EP07024609A EP1937011B1 EP 1937011 B1 EP1937011 B1 EP 1937011B1 EP 07024609 A EP07024609 A EP 07024609A EP 1937011 B1 EP1937011 B1 EP 1937011B1
Authority
EP
European Patent Office
Prior art keywords
sub
client stations
antenna
signals
sector
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Active
Application number
EP07024609.5A
Other languages
German (de)
French (fr)
Other versions
EP1937011A1 (en
Inventor
Walid Bendenia
Mickaël Batariere
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Sagemcom Broadband SAS
Original Assignee
Sagemcom Broadband SAS
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Sagemcom Broadband SAS filed Critical Sagemcom Broadband SAS
Publication of EP1937011A1 publication Critical patent/EP1937011A1/en
Application granted granted Critical
Publication of EP1937011B1 publication Critical patent/EP1937011B1/en
Active legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Images

Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W16/00—Network planning, e.g. coverage or traffic planning tools; Network deployment, e.g. resource partitioning or cells structures
    • H04W16/24—Cell structures
    • H04W16/30—Special cell shapes, e.g. doughnuts or ring cells
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W16/00—Network planning, e.g. coverage or traffic planning tools; Network deployment, e.g. resource partitioning or cells structures
    • H04W16/02—Resource partitioning among network components, e.g. reuse partitioning
    • H04W16/10—Dynamic resource partitioning
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W52/00—Power management, e.g. TPC [Transmission Power Control], power saving or power classes
    • H04W52/04—TPC
    • H04W52/38—TPC being performed in particular situations
    • H04W52/42—TPC being performed in particular situations in systems with time, space, frequency or polarisation diversity

Definitions

  • the invention relates to the field of radio telecommunications and more specifically the management of the radio resource in such a system. It is, in particular, a technique of dynamic allocation of sub-sectors by a base station in such a system.
  • Modern radio communication systems and in particular so-called cellular systems, use various means of sharing the radio resource among the multiple users of the system. To do this, various techniques are used. It is possible to share the time which leads to so-called TDMA systems ("Time Division Multiple Access" in English) where each user is reserved a period of time for his communications. It is also possible to share the frequencies. In this case, the frequency band is divided into subbands distributed among the different users. Each subband may use one or more subcarriers. In the context of a system based on the sharing of the frequency band in sub-carriers, in order to be able to use neighboring sub-bands and thus obtain a better use of the resource, it is then advantageous to choose orthogonal subcarriers.
  • the radio resource of an OFDMA system can be represented as a time-frequency table as shown in FIG. Fig. 1 where each line corresponds to a subcarrier of the frequency band used and each column to a period of time.
  • the elementary units corresponding to a period of time and a given subcarrier define a radio resource unit that can be allocated.
  • This system is used, for example, in the system known as WIMAX according to the standard "IEEES02.16 ° -2005".
  • Such communication systems are called cellular when the communication is organized by cell.
  • Each cell is composed of an access point consisting of a base station, BS ("Base Station” in English) and a plurality of SS client stations ("Subscriber Station” in English). All communications are established between the base station and a client station. It follows that when two client stations want to communicate, these calls necessarily pass through the base station.
  • a frequency band defines a communication channel. This channel is used for communication between the base station and the client stations.
  • the Fig. 2 defines the transmission chain corresponding to a transmission channel for a given sector in the prior art.
  • a sector is defined by the system transmitting on a communication channel and all the client stations with which it can communicate.
  • This chain is composed of a transceiver 2.2 exchanging digital data 2.1 with a data network, on the one hand, and composing the signals to be transmitted 2.3 in baseband, on the other hand.
  • These signals to be transmitted 2.3 are transmitted to an RF (Radio Frequency) module 2.4 responsible for transposing the frequency of the signal in the band corresponding to the channel used and transmitting the signal via the antenna 2.5.
  • RF Radio Frequency
  • This antenna may consist of an antenna array, for example as part of a MIMO transmission ("Multiple Input Multiple Output"). These signals are then received by a client station via its antenna 2.6 and processed by a module 2.7 combining the functions of RF module and digital transceiver that will provide the data in digital form 2.8 to the customer.
  • MIMO transmission Multiple Input Multiple Output
  • a base station can handle multiple sectors defining multiple cells as illustrated on the Fig. 3 .
  • a base station with three sectors defining three cells, each sector being defined by a transmission chain like the one shown in the figure. Fig. 2 and therefore having its own antenna, or antenna array.
  • the customer stations present in the sector will be divided into three zones represented here by the letter, 1a, 1b and 1c for the first sector, according to the transmission power necessary to reach them. In this way, it is possible to use only the power required when transmitting data exclusively for client stations belonging to one of these zones.
  • the transmission power is distributed over the frequency band used. Therefore, the maximum power available to the transmitter defines the maximum transmit power of a sub-band and thus the range of the transmitter. In such a system, it is advantageous to have the maximum range while maximizing the use of the radio resource and keeping the cost of the system as low as possible.
  • the document WO 97/40594 discloses a wireless communications system in which the transmission channel is defined by a frequency band and a TDMA transmission at frequencies of the band. It uses antennas composed of a set of elementary antennas, the modulation of the transmission power on a frequency being done by varying the number of elementary antennas assigned to the transmission of the signal on this frequency.
  • the invention proposes a new management of a radio transmission channel in a cellular radio communication system based on the use of several antennas allowing a dynamic spectrum management available for a sector in sub-sectors managed by the same transceiver digital.
  • This dynamic management includes dynamic management of channel frequency resource allocation and dynamic allocation of available transmit power between different sub-sectors.
  • the allocation of these subsectors within the communication channel as well as the transmission powers of the signals corresponding to these sub-sectors are dynamically coordinated so as to allow a good use of the radio resource.
  • the invention is defined by independent claims 1 and 7.
  • the step of modulating the transmission power of the signals corresponding to each sub-sector comprises a step of multiplication by a coefficient (w1, w2) of the data to be transmitted beforehand. generating the baseband signal by inverse Fourier transform within the transceiver.
  • the step of modulating the transmission power of the signals corresponding to each sub-sector comprises a parametric amplification step (p1, p2) of the signals to be transmitted.
  • the sharing of the bandwidth is done on the basis of frequency subbands.
  • the sharing unit is the subcarrier of the system.
  • the sharing of the bandwidth is done on the basis of a code distribution in a system based on code division multiple access, CDMA.
  • the means for modulating the transmission power of the different signals comprise means of multiplying by a scalar (w1, w2) the data to be transmitted prior to the generation of the baseband signal by inverse Fourier transform within the transceiver.
  • the means for modulating the transmission power of the various signals comprise parametric amplification means (p1, p2) of the signals to be transmitted.
  • the sharing of the bandwidth is done on the basis of frequency subbands.
  • the sharing unit is the subcarrier of the system.
  • the sharing of the bandwidth is done on the basis of a code distribution in a system based on code division multiple access, CDMA.
  • Scope is one of the most important aspects of cellular communication systems in that it determines the number of base stations to be deployed to cover a given territory. The range is determined by the gain of the antenna and the power of emission. The more directional an antenna, the higher its gain. This is one of the reasons for the division of cells into sectors covered by more directive antennas and therefore of higher gain than an omnidirectional antenna. On the other hand, the more the number of sectors the more the cost of the base station increases because of the multiplication of the transmission channels, digital transceiver, RF module and antenna, to be used.
  • the other important aspect is also the bandwidth of the system.
  • This bandwidth is directly related to the utilization rate of the radio resource and therefore of each communication channel used.
  • Spectral efficiency refers to the amount of information transmitted in a given time on a given frequency band.
  • the frequency band usable in such systems is generally limited, the sector division of cells allows an increase in the bandwidth only if the size of the communication channel, therefore the frequency band allocated to it, remains the same.
  • an operator has only a limited number of communication channels to deploy his network.
  • the basic idea of the invention is to distribute the communication between the base station and the client stations of the same sector between several antennas. These different antennas share the communication channel associated with the sector.
  • This provision is illustrated by the Fig. 4 where the first sector of the cell represented in the Fig. 3 is now served by two antennas.
  • the fact of using two or more antennas instead of just one already allows a range gain due to the fact that we will use more directional antennas.
  • it can be an antenna network, operating for example in MIMO.
  • the sector is divided into sub-sectors that cover only part of the initial sector. All of these sub-sectors cover the extent of the initial sector, or even a little more because of the gain in scope.
  • the different client stations in the area covered by the sector are divided into groups of client stations according to the transmission power required to establish communication between the base station and its stations. customers by maintaining the performance of this communication.
  • This transmission power depends on the quality of the transmission between the base station and the client station and therefore the environment and the distance separating these two stations. It is evaluated by measuring the transmission quality by known measures such as the measurement of the received power, for example. It is also possible to collect measurements made by the stations themselves or to use any method of measuring the quality of the transmission.
  • These data can be stored in a database at the base station level to be used for the distribution of the client stations into groups. This distribution is dynamic and evolves over time, depending on the evolution of the radio context and the possible shift of the client stations.
  • the Fig. 4 shows us a sector divided into two sub-sectors 1 and 2, the client stations being classified in groups 1a, 1b, 1c, 2a, 2b, 2c.
  • the Fig. 4 shows a schematic situation where group membership seems to depend solely on the distance to the base station. It is obvious that in a real situation where the quality of transmission is dependent on the environment, the boundaries between groups and sub-sectors are not as geometrically delimited.
  • the transmission power is distributed over the entire frequency band used, it is possible to increase the transmission power to reach remote client stations or in an unfavorable radio environment by reducing this frequency band.
  • the frequency band is divided into subbands, the emission can be reduced to certain subbands.
  • the number of subcarriers used is reduced. If only half of the subcarriers are used, for example, a gain in transmission power of 3 dB is obtained.
  • the use of this technique therefore makes it possible to increase the range of the signal but leads in a conventional implementation, obviously, to an under-utilization of the channel because one is prohibited from transmitting on certain parts of the frequency band which are reserved by the channel. This limitation is circumvented by the exemplary embodiment of the invention.
  • the exemplary embodiment is placed in the context of an OFDMA transmission where the frequency band is divided into a set of sub-carriers.
  • the communication channel that is to say all the sub-carriers of the frequency band of the considered channel as a function of time, will be distributed between the different sub-sectors and within the sub-sectors according to the different groups of client stations.
  • each antenna constituting the sector transmits only a subset of the sub-carriers of the channel according to a transmission power adapted to the group of destination client stations. Since the total transmission power on the communication channel, all antennas included, is limited, on the one hand, by the capabilities of the transmission system and, on the other hand, by the need to reasonably limit the level of transmission.
  • the communication channel it is advantageous for a good use of the communication channel to emit at a low power on one antenna when one emits high power on the other or one of the others.
  • the released subcarriers can be used for transmission by one or more other antennas for transmissions to groups of client stations not requiring high transmission power.
  • Fig. 5a and 5b illustrate the evolution over time of the power spectral density (DSP) of the signal sent and the average transmission power of the signals sent on the two antennas of the embodiment of the invention.
  • the Fig. 5a illustrates the signal of the first sub-sector while the Fig. 5b illustrates the signal of the second sub-sector.
  • DSP power spectral density
  • sub-sector 1 Synchronously, on the second antenna, while sub-sector 1 is transmitting at low power on group a the rest of the bandwidth, the remaining quarter is used at full power for transmission to group c of the sub-sector. sector 2. While sub-sector 1 transmits the remaining bandwidth at high power on group b, the remaining quarter is always used at full power for transmission to subsector group 2. In a second time, it is sub-sector 1 that uses the power increase technique for group c while subsector 2 sends data on the rest of the spectrum to group b and then in a second time to power reduced to group a.
  • the Fig. 6 illustrates the architecture of the base station for a sector according to an exemplary embodiment of the invention.
  • This example remains in the context of an implementation based on two sub-sectors and two antennas, but it is spreading immediately to a larger number of sub-sectors and antennas.
  • It shows the digital transceiver composed of a MAC layer ("Medium Access Control" in English) which accesses the database 6.1 containing information on the membership of different groups of different client stations. Within this MAC layer, the data to be transmitted are therefore grouped according to the recipient groups. It is also this layer 6.2 which manages the allocation of the sub-carriers to the different sub-sectors. It also manages power allocations between different sub-sectors.
  • MAC layer Medium Access Control
  • the data is divided according to the destination group in different bursts ("burst" in English) of data distributed within the communication channel.
  • the data thus organized are sent to a module 6.3 responsible for calculating the redundancy codes and converting the data into transmission symbols. These symbols are then, according to their belonging to the data bursts, distributed among several, here two, inverse Fourier transform modules 6.4 and 6.5 to generate the baseband signal for transmission to the RF module.
  • a multiplication by a coefficient allows a first adjustment of the power of the signal that will be generated for each output.
  • These parameters, here w1 and w2 are calculated by the MAC module 6.2.
  • the Fig. 7 schematically illustrates the WIMAX frame in TDD ("Time Division Duplex") comprising two phases.
  • DL Down Link
  • the communication starts with the transmission of a preamble 7.1 transmitted over the entire channel and information on the allocation of the resource radio for this downward phase.
  • UL Up Link
  • the various data bursts issued 7.3.
  • the channel is occupied by the data bursts 7.4.
  • the IEEE802.16 standard supports the ability to send data bursts to the downstream channel in a dedicated mode (STC zone), in which the client stations concerned only use the necessary drivers to decode their bursts and not all the pilots. issued by the base station.
  • STC zone dedicated mode
  • the cutting of the data according to the different groups of the different sub-sectors uses this burst division and will allocate the different bursts to the different sub-sectors and groups of client stations.
  • the transmission power of the different bursts can be adjusted by means of the "power boosting" field provided in the DL MAP IE structure used to describe the allocation of radio resources in the standard.
  • the data of each burst is sent in a particular physical mode.
  • This physical mode is defined by the modulation used containing more or fewer symbols and by the choice of the error correcting code chosen.
  • the higher the quality of the transmission the more it is possible to choose a modulation using a large number of symbols and a correction code providing little redundancy.
  • the transmission quality is less good, it is necessary to use a more robust physical mode consisting of a modulation using a lesser number of symbols and a corrector code providing more redundancy.
  • the invention makes it possible to transmit punctually with a greater power of emission to effectively combat the level of noise and interference perceived by the client stations. It thus makes it possible to use less robust physical modes increasing the bandwidth of the transmission channel by the same amount.
  • the invention also makes it possible to statistically reduce the energy emitted in each sub-sector, which significantly reduces the level of interference for neighboring cells.
  • the invention described herein as part of the WIMAX cellular transmission system may be used in any type of communication network between an access point and client stations based on a transmission sharing the radio resource, on the one hand, on a time basis and, on the other hand, on a frequency basis.
  • CDMA code division multiple access
  • the different Coded signals with their respective codes are sent via the different antennas with a suitable power according to the invention. It makes it possible to improve the use of the transmission channel by multiplying the number of antennas used to cover a sector without requiring the multiplication of the corresponding transceiver modules. It makes it possible to increase the range of the system while guaranteeing a very good use of the radio resource of the transmission channel and a good bandwidth.

Landscapes

  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Mobile Radio Communication Systems (AREA)

Description

L'invention concerne le domaine des télécommunications radio et plus précisément la gestion de la ressource radio dans un tel système. Il s'agit, en particulier, d'une technique d'allocation dynamique de sous-secteurs par une station de base dans un tel système.The invention relates to the field of radio telecommunications and more specifically the management of the radio resource in such a system. It is, in particular, a technique of dynamic allocation of sub-sectors by a base station in such a system.

Les systèmes de télécommunication modernes par radio, et en particulier les systèmes dits cellulaires, utilisent divers moyens de partager la ressource radio entre les multiples utilisateurs du système. Pour ce faire, diverses techniques sont utilisées. Il est possible de partager le temps ce qui conduit à des systèmes dits TDMA (« Time Division Multiple Access » en anglais) où chaque utilisateur se voit réserver une période de temps pour ses communications. Il est également possible de partager les fréquences. Dans ce cas, la bande de fréquence est divisée en sous-bandes réparties entre les différents utilisateurs. Chaque sous-bande peut utiliser une ou plusieurs sous-porteuses. Dans le cadre d'un système basé sur le partage de la bande de fréquence en sous-porteuses, pour pouvoir utiliser des sous-bandes proches et donc obtenir une meilleure utilisation de la ressource, il est alors avantageux de choisir des sous-porteuses orthogonales entre elles pour limiter les interférences entre sous-porteuses. Ce système est appelé OFDMA (« Orthogonal Frequency Division Multiple Access » en anglais), c'est-à-dire système à accès multiple par répartition en fréquences orthogonales. La ressource radio d'un système OFDMA peut être représentée sous la forme d'un tableau temps fréquence comme illustré à la Fig. 1 où chaque ligne correspond à une sous-porteuse de la bande de fréquence utilisée et chaque colonne à une période de temps. Les unités élémentaires correspondant à une période de temps et à une sous-porteuse donnée définissent une unité de ressource radio pouvant être allouée. Ce système est utilisé, par exemple, dans le système connu sous le nom de WIMAX conforme à la norme « IEEES02.16°-2005 ».Modern radio communication systems, and in particular so-called cellular systems, use various means of sharing the radio resource among the multiple users of the system. To do this, various techniques are used. It is possible to share the time which leads to so-called TDMA systems ("Time Division Multiple Access" in English) where each user is reserved a period of time for his communications. It is also possible to share the frequencies. In this case, the frequency band is divided into subbands distributed among the different users. Each subband may use one or more subcarriers. In the context of a system based on the sharing of the frequency band in sub-carriers, in order to be able to use neighboring sub-bands and thus obtain a better use of the resource, it is then advantageous to choose orthogonal subcarriers. between them to limit interference between sub-carriers. This system is called OFDMA (Orthogonal Frequency Division Multiple Access) in English), that is orthogonal frequency division multiple access system. The radio resource of an OFDMA system can be represented as a time-frequency table as shown in FIG. Fig. 1 where each line corresponds to a subcarrier of the frequency band used and each column to a period of time. The elementary units corresponding to a period of time and a given subcarrier define a radio resource unit that can be allocated. This system is used, for example, in the system known as WIMAX according to the standard "IEEES02.16 ° -2005".

De tels systèmes de communication sont dits cellulaires lorsque la communication est organisée par cellule. Chaque cellule est composée d'un point d'accès constitué d'une station de base, BS (« Base Station » en anglais) et d'une pluralité de stations clientes SS (« Subscriber Station » en anglais). Toutes les communications sont établies entre la station de base et une station cliente. Il s'ensuit que lorsque deux stations clientes veulent communiquer, ces communications passent obligatoirement par la station de base. Dans un tel système, une bande de fréquence définit un canal de communication. Ce canal est utilisé pour la communication entre la station de base et les stations clientes. La Fig. 2 définit la chaîne de transmission correspondant à un canal de transmission pour un secteur donné dans l'art antérieur. Un secteur est défini par le système émettant sur un canal de communication et toutes les stations clientes avec lesquelles il peut communiquer. Nous parlerons donc de cellule pour définir l'espace géographique défini par une station de base communiquant sur un canal de transmission donné et l'ensemble de stations clientes avec lesquelles la communication est possible depuis cette station de base sur le canal considéré. Nous parlerons de secteur pour parler plus précisément de la chaîne des équipements permettant cette communication associée. Cette chaîne est composée d'un émetteur-récepteur 2.2 échangeant des données numériques 2.1 avec un réseau de données, d'une part, et composant les signaux à émettre 2.3 en bande de base, d'autre part. Ces signaux à émettre 2.3 sont transmis à un module RF (Radio Fréquence) 2.4 chargé de transposer la fréquence du signal dans la bande correspondant au canal utilisé et d'émettre le signal via l'antenne 2.5. Cette antenne peut être constituée d'un réseau d'antenne, par exemple dans le cadre d'une transmission MIMO (« Multiple Input Multiple Output » en anglais). Ces signaux sont alors reçus par une station cliente via son antenne 2.6 et traités par un module 2.7 combinant les fonctions de module RF et d'émetteur-récepteur numérique qui va fournir les données sous forme numérique 2.8 au client.Such communication systems are called cellular when the communication is organized by cell. Each cell is composed of an access point consisting of a base station, BS ("Base Station" in English) and a plurality of SS client stations ("Subscriber Station" in English). All communications are established between the base station and a client station. It follows that when two client stations want to communicate, these calls necessarily pass through the base station. In such a system, a frequency band defines a communication channel. This channel is used for communication between the base station and the client stations. The Fig. 2 defines the transmission chain corresponding to a transmission channel for a given sector in the prior art. A sector is defined by the system transmitting on a communication channel and all the client stations with which it can communicate. We will therefore talk about cell to define the geographical space defined by a base station communicating on a given transmission channel and the set of client stations with which communication is possible from this base station on the channel considered. We will talk about sector to speak more precisely of the chain of equipment allowing this associated communication. This chain is composed of a transceiver 2.2 exchanging digital data 2.1 with a data network, on the one hand, and composing the signals to be transmitted 2.3 in baseband, on the other hand. These signals to be transmitted 2.3 are transmitted to an RF (Radio Frequency) module 2.4 responsible for transposing the frequency of the signal in the band corresponding to the channel used and transmitting the signal via the antenna 2.5. This antenna may consist of an antenna array, for example as part of a MIMO transmission ("Multiple Input Multiple Output"). These signals are then received by a client station via its antenna 2.6 and processed by a module 2.7 combining the functions of RF module and digital transceiver that will provide the data in digital form 2.8 to the customer.

Une station de base peut gérer plusieurs secteurs définissant plusieurs cellules comme illustrés sur la Fig. 3. Sur cette figure, nous voyons une station de base comportant trois secteurs définissant trois cellules, chaque secteur étant défini par une chaîne de transmission comme celle illustrée sur la Fig. 2 et possédant donc sa propre antenne, ou réseau d'antenne. Les stations clientes présentes dans le secteur vont être réparties en trois zones ici représentées par la lettre, 1a, 1b et 1c pour le premier secteur, en fonction de la puissance d'émission nécessaire pour les atteindre. De cette façon, il est possible de n'utiliser que la puissance nécessaire lorsque l'on émet des données à destination exclusive de stations clientes appartenant à l'une de ces zones.A base station can handle multiple sectors defining multiple cells as illustrated on the Fig. 3 . In this figure, we see a base station with three sectors defining three cells, each sector being defined by a transmission chain like the one shown in the figure. Fig. 2 and therefore having its own antenna, or antenna array. The customer stations present in the sector will be divided into three zones represented here by the letter, 1a, 1b and 1c for the first sector, according to the transmission power necessary to reach them. In this way, it is possible to use only the power required when transmitting data exclusively for client stations belonging to one of these zones.

Dans un système de transmission radio, la puissance d'émission se répartit sur la bande de fréquence utilisée. Donc, la puissance maximum disponible à l'émetteur définit la puissance maximum d'émission d'une sous-bande et de ce fait la portée de l'émetteur. Dans un tel système, il est avantageux d'avoir la portée maximale tout en maximisant l'utilisation de la ressource radio et en maintenant un coût du système le plus bas possible. Le document WO 97/40594 décrit un système de communications sans fil dans lequel le canal de transmission est défini par une bande de fréquence et une transmission de type TDMA sur des fréquences de la bande. Il utilise des antennes composées d'un ensemble d'antennes élémentaires, la modulation de la puissance d'émission sur une fréquence se faisant en faisant varier le nombre d'antennes élémentaires attribué à l'émission du signal sur cette fréquence. L'invention propose une nouvelle gestion d'un canal de transmission radio dans un système de communication radio cellulaire basée sur l'utilisation de plusieurs antennes permettant une gestion dynamique du spectre disponible pour un secteur en sous-secteurs gérés par un même émetteur-récepteur numérique. Cette gestion dynamique comprend une gestion dynamique de l'allocation de la ressource de fréquence du canal et l'allocation dynamique de la puissance d'émission disponible entre les différents sous-secteurs. L'allocation de ces sous-secteurs au sein du canal de communication ainsi que les puissances d'émission des signaux correspondant à ces sous-secteurs sont coordonnées dynamiquement de façon à permettre une bonne utilisation de la ressource radio. L'invention est définie par les revendications indépendantes 1 et 7. Selon un mode particulier de réalisation de l'invention, l'étape de modulation de la puissance d'émission des signaux correspondant à chaque sous-secteur comporte une étape de multiplication par un coefficient (w1, w2) des données à émettre préalablement à la génération du signal en bande de base par transformée de Fourier inverse au sein de l'émetteur-récepteur.In a radio transmission system, the transmission power is distributed over the frequency band used. Therefore, the maximum power available to the transmitter defines the maximum transmit power of a sub-band and thus the range of the transmitter. In such a system, it is advantageous to have the maximum range while maximizing the use of the radio resource and keeping the cost of the system as low as possible. The document WO 97/40594 discloses a wireless communications system in which the transmission channel is defined by a frequency band and a TDMA transmission at frequencies of the band. It uses antennas composed of a set of elementary antennas, the modulation of the transmission power on a frequency being done by varying the number of elementary antennas assigned to the transmission of the signal on this frequency. The invention proposes a new management of a radio transmission channel in a cellular radio communication system based on the use of several antennas allowing a dynamic spectrum management available for a sector in sub-sectors managed by the same transceiver digital. This dynamic management includes dynamic management of channel frequency resource allocation and dynamic allocation of available transmit power between different sub-sectors. The allocation of these subsectors within the communication channel as well as the transmission powers of the signals corresponding to these sub-sectors are dynamically coordinated so as to allow a good use of the radio resource. The invention is defined by independent claims 1 and 7. According to a particular embodiment of the invention, the step of modulating the transmission power of the signals corresponding to each sub-sector comprises a step of multiplication by a coefficient (w1, w2) of the data to be transmitted beforehand. generating the baseband signal by inverse Fourier transform within the transceiver.

Selon un mode particulier de réalisation de l'invention, l'étape de modulation de la puissance d'émission des signaux correspondant à chaque sous-secteur comporte une étape d'amplification paramétrée (p1, p2) des signaux à émettre.According to a particular embodiment of the invention, the step of modulating the transmission power of the signals corresponding to each sub-sector comprises a parametric amplification step (p1, p2) of the signals to be transmitted.

Selon un mode particulier de réalisation de l'invention, le partage de la bande passante se fait sur la base de sous-bandes de fréquence.According to a particular embodiment of the invention, the sharing of the bandwidth is done on the basis of frequency subbands.

Selon un mode particulier de réalisation de l'invention, le système étant basé sur un accès multiple par répartition en fréquences orthogonales, OFDM, l'unité de partage est la sous-porteuse du système.According to a particular embodiment of the invention, the system being based on orthogonal frequency division multiple access, OFDM, the sharing unit is the subcarrier of the system.

Selon un mode particulier de réalisation de l'invention, le partage de la bande passante se fait sur la base d'une répartition en code dans un système basé sur un accès multiple par répartition en code, CDMA.According to a particular embodiment of the invention, the sharing of the bandwidth is done on the basis of a code distribution in a system based on code division multiple access, CDMA.

Selon un mode particulier de réalisation du dispositif, les moyens de modulation de la puissance d'émission des différents signaux comprennent des moyens de multiplier par un scalaire (w1, w2) les données à émettre préalablement à la génération du signal en bande de base par transformée de Fourier inverse au sein de l'émetteur-récepteur.According to a particular embodiment of the device, the means for modulating the transmission power of the different signals comprise means of multiplying by a scalar (w1, w2) the data to be transmitted prior to the generation of the baseband signal by inverse Fourier transform within the transceiver.

Selon un mode particulier de réalisation du dispositif les moyens de modulation de la puissance d'émission des différents signaux comprennent des moyens d'amplification paramétrée (p1, p2) des signaux à émettre.According to a particular embodiment of the device, the means for modulating the transmission power of the various signals comprise parametric amplification means (p1, p2) of the signals to be transmitted.

Selon un mode particulier de réalisation du dispositif le partage de la bande passante se fait sur la base de sous-bandes de fréquence.According to a particular embodiment of the device the sharing of the bandwidth is done on the basis of frequency subbands.

Selon un mode particulier de réalisation du dispositif le système étant basé sur un accès multiple par répartition en fréquences orthogonales, OFDM, l'unité de partage est la sous-porteuse du système.According to a particular embodiment of the device, the system being based on orthogonal frequency division multiple access, OFDM, the sharing unit is the subcarrier of the system.

Selon un mode particulier de réalisation du dispositif le partage de la bande passante se fait sur la base d'une répartition en code dans un système basé sur un accès multiple par répartition en code, CDMA.According to a particular embodiment of the device the sharing of the bandwidth is done on the basis of a code distribution in a system based on code division multiple access, CDMA.

Les caractéristiques de l'invention mentionnées ci-dessus, ainsi que d'autres, apparaîtront plus clairement à la lecture de la description suivante d'un exemple de réalisation, ladite description étant faite en relation avec les dessins joints, parmi lesquels :

  • la Fig. 1 décrit une représentation de la ressource radio dans un système OFDMA.
  • La Fig. 2 décrit l'architecture de la chaîne de transmission dans l'art antérieur.
  • La Fig. 3 décrit l'organisation d'un exemple de station de base dans l'art antérieur.
  • La Fig. 4 décrit l'organisation d'un secteur dans un exemple de réalisation de l'invention.
  • La Fig. 5 décrit la répartition de la puissance spectrale d'émission et l'utilisation de la bande de fréquence dans l'exemple de réalisation de l'invention.
  • La Fig. 6 décrit l'architecture du système d'émission de l'exemple de réalisation de l'invention.
  • La Fig. 7 décrit schématiquement la structure de la trame d'un système selon le standard WIMAX (ou la norme IEEE802.16).
The characteristics of the invention mentioned above, as well as others, will appear more clearly on reading the following description of an exemplary embodiment, said description being given in relation to the attached drawings, among which:
  • the Fig. 1 describes a representation of the radio resource in an OFDMA system.
  • The Fig. 2 describes the architecture of the transmission chain in the prior art.
  • The Fig. 3 describes the organization of an exemplary base station in the prior art.
  • The Fig. 4 describes the organization of a sector in an exemplary embodiment of the invention.
  • The Fig. 5 describes the distribution of the transmit spectral power and the use of the frequency band in the exemplary embodiment of the invention.
  • The Fig. 6 describes the architecture of the transmission system of the exemplary embodiment of the invention.
  • The Fig. 7 schematically describes the frame structure of a system according to the WIMAX standard (or the IEEE802.16 standard).

La portée est un des aspects les plus importants des systèmes de communication cellulaires en ce qu'elle détermine le nombre de stations de base devant être déployées pour couvrir un territoire donné. La portée est déterminée par le gain de l'antenne et par la puissance d'émission. Plus une antenne est directive et plus son gain est élevé. C'est une des raisons de la division des cellules en secteurs couverts par des antennes plus directives et donc de gain plus élevé qu'une antenne omnidirectionnelle. D'un autre côté, plus on multiplie le nombre de secteurs plus le coût de la station de base augmente du fait de la multiplication des chaînes d'émission, émetteur-récepteur numérique, module RF et antenne, devant être utilisés.Scope is one of the most important aspects of cellular communication systems in that it determines the number of base stations to be deployed to cover a given territory. The range is determined by the gain of the antenna and the power of emission. The more directional an antenna, the higher its gain. This is one of the reasons for the division of cells into sectors covered by more directive antennas and therefore of higher gain than an omnidirectional antenna. On the other hand, the more the number of sectors the more the cost of the base station increases because of the multiplication of the transmission channels, digital transceiver, RF module and antenna, to be used.

L'autre aspect important est également la bande passante du système. Cette bande passante est directement liée au taux d'utilisation de la ressource radio et donc de chaque canal de communication utilisé. On parle d'efficacité spectrale pour désigner la quantité d'informations transmises en un temps donné sur une bande de fréquence donnée. Comme la bande de fréquence utilisable dans de tels systèmes est généralement limitée, le découpage en secteur des cellules ne permet une augmentation de la bande passante que si la taille du canal de communication, donc la bande de fréquence qui lui est allouée, reste la même. Généralement un opérateur ne dispose que d'un nombre limité de canaux de communication pour déployer son réseau.The other important aspect is also the bandwidth of the system. This bandwidth is directly related to the utilization rate of the radio resource and therefore of each communication channel used. Spectral efficiency refers to the amount of information transmitted in a given time on a given frequency band. As the frequency band usable in such systems is generally limited, the sector division of cells allows an increase in the bandwidth only if the size of the communication channel, therefore the frequency band allocated to it, remains the same. Generally an operator has only a limited number of communication channels to deploy his network.

L'idée de base de l'invention est de répartir la communication entre la station de base et les stations clientes d'un même secteur entre plusieurs antennes. Ces différentes antennes se partagent le canal de communication associé au secteur. Cette disposition est illustrée par la Fig. 4 où le premier secteur de la cellule représentée à la Fig. 3 est maintenant servi par deux antennes. Le fait d'utiliser deux, ou plus, antennes au lieu d'une seule permet déjà un gain de portée dû au fait que l'on va utiliser des antennes plus directionnelles. Lorsque nous parlons d'une antenne, il peut s'agir d'un réseau d'antennes, fonctionnant par exemple en MIMO.The basic idea of the invention is to distribute the communication between the base station and the client stations of the same sector between several antennas. These different antennas share the communication channel associated with the sector. This provision is illustrated by the Fig. 4 where the first sector of the cell represented in the Fig. 3 is now served by two antennas. The fact of using two or more antennas instead of just one already allows a range gain due to the fact that we will use more directional antennas. When we talk about an antenna, it can be an antenna network, operating for example in MIMO.

Le secteur est divisé en sous-secteurs qui couvrent seulement une partie du secteur initial. L'ensemble de ces sous-secteurs couvre l'étendue du secteur initial, voire un peu plus du fait du gain en portée. D'un autre côté, les différentes stations clientes se trouvant dans l'aire couverte par le secteur sont réparties au sein de groupes de stations clientes en fonction de la puissance d'émission nécessaire pour établir une communication entre la station de base et ses stations clientes en maintenant la performance de cette communication. Cette puissance d'émission dépend de la qualité de la transmission entre la station de base et la station cliente et donc de l'environnement et de la distance séparant ces deux stations. Elle est évaluée par mesure de la qualité de transmission par des mesures connues telles que la mesure de la puissance reçue, par exemple. Il est également possible de collecter des mesures faites par les stations elles-mêmes ou d'utiliser tout procédé de mesure de la qualité de la transmission. Ces données peuvent être conservées dans une base de données au niveau de la station de base pour servir à la répartition des stations clientes en groupes. Cette répartition est dynamique et évolue dans le temps en fonction de l'évolution du contexte radio et du déplacement éventuel des stations clientes.The sector is divided into sub-sectors that cover only part of the initial sector. All of these sub-sectors cover the extent of the initial sector, or even a little more because of the gain in scope. On the other hand, the different client stations in the area covered by the sector are divided into groups of client stations according to the transmission power required to establish communication between the base station and its stations. customers by maintaining the performance of this communication. This transmission power depends on the quality of the transmission between the base station and the client station and therefore the environment and the distance separating these two stations. It is evaluated by measuring the transmission quality by known measures such as the measurement of the received power, for example. It is also possible to collect measurements made by the stations themselves or to use any method of measuring the quality of the transmission. These data can be stored in a database at the base station level to be used for the distribution of the client stations into groups. This distribution is dynamic and evolves over time, depending on the evolution of the radio context and the possible shift of the client stations.

La Fig. 4 nous montre donc un secteur divisé en deux sous-secteurs 1 et 2, les stations clientes étant classées dans les groupes 1a, 1b, 1c, 2a, 2b, 2c. La Fig. 4 montre une situation schématique où l'appartenance au groupe semble dépendre uniquement de la distance à la station de base. Il est évident que dans une situation réelle où la qualité de la transmission est dépendante de l'environnement, les frontières entre les groupes et entre les sous-secteurs ne sont pas aussi bien délimitées de façon géométrique.The Fig. 4 shows us a sector divided into two sub-sectors 1 and 2, the client stations being classified in groups 1a, 1b, 1c, 2a, 2b, 2c. The Fig. 4 shows a schematic situation where group membership seems to depend solely on the distance to the base station. It is obvious that in a real situation where the quality of transmission is dependent on the environment, the boundaries between groups and sub-sectors are not as geometrically delimited.

La puissance d'émission étant répartie sur toute la bande de fréquence utilisée, il est possible d'augmenter la puissance d'émission pour atteindre des stations clientes distantes ou dans un environnement radio défavorable, par une réduction de cette bande de fréquence. Quand la bande de fréquence est divisée en sous-bandes, on peut réduire l'émission à certaines sous-bandes. Dans le cas d'une émission sur des sous-porteuses, on réduit le nombre de sous-porteuses utilisées. Si on n'utilise que la moitié des sous-porteuses, par exemple, on obtient un gain en puissance d'émission de 3 dB. L'utilisation de cette technique permet donc d'augmenter la portée du signal mais conduit dans une implémentation classique, de manière évidente, à une sous-utilisation du canal car on s'interdit d'émettre sur certaines parties de la bande de fréquence qui sont réservées par le canal. Cette limitation est contournée par l'exemple de réalisation de l'invention.Since the transmission power is distributed over the entire frequency band used, it is possible to increase the transmission power to reach remote client stations or in an unfavorable radio environment by reducing this frequency band. When the frequency band is divided into subbands, the emission can be reduced to certain subbands. In the case of a transmission on subcarriers, the number of subcarriers used is reduced. If only half of the subcarriers are used, for example, a gain in transmission power of 3 dB is obtained. The use of this technique therefore makes it possible to increase the range of the signal but leads in a conventional implementation, obviously, to an under-utilization of the channel because one is prohibited from transmitting on certain parts of the frequency band which are reserved by the channel. This limitation is circumvented by the exemplary embodiment of the invention.

L'exemple de réalisation se place dans le cadre d'une transmission de type OFDMA où la bande de fréquence est répartie en un ensemble de sous-porteuses. Dans un tel cadre, le canal de communication, c'est-à-dire l'ensemble des sous-porteuses de la bande de fréquence du canal considéré en fonction du temps, va être réparti entre les différents sous-secteurs et au sein des sous-secteurs en fonction des différents groupes de stations clientes. De cette façon, à un instant donné, chaque antenne constituant le secteur émet uniquement un sous-ensemble des sous-porteuses du canal selon une puissance d'émission adaptée au groupe de stations clientes destinataires. Comme la puissance d'émission totale sur le canal de communication, toutes antennes comprises, est limitée, d'une part, par les capacités du système d'émission et, d'autre part, par la nécessité de limiter raisonnablement le niveau d'interférence, il est avantageux pour une bonne utilisation du canal de communication d'émettre à une puissance faible sur une antenne quand on émettra à forte puissance sur l'autre ou l'une des autres. De cette façon, lorsqu'une des antennes émet à forte puissance sur un nombre limité de sous-porteuses selon la technique précédemment décrite d'augmentation de la portée, les sous-porteuses libérées peuvent être utilisées pour l'émission par une ou plusieurs autres antennes pour des émissions à destination de groupes de stations clientes ne nécessitant pas une forte puissance d'émission.The exemplary embodiment is placed in the context of an OFDMA transmission where the frequency band is divided into a set of sub-carriers. In such a framework, the communication channel, that is to say all the sub-carriers of the frequency band of the considered channel as a function of time, will be distributed between the different sub-sectors and within the sub-sectors according to the different groups of client stations. In this way, at a given moment, each antenna constituting the sector transmits only a subset of the sub-carriers of the channel according to a transmission power adapted to the group of destination client stations. Since the total transmission power on the communication channel, all antennas included, is limited, on the one hand, by the capabilities of the transmission system and, on the other hand, by the need to reasonably limit the level of transmission. interference, it is advantageous for a good use of the communication channel to emit at a low power on one antenna when one emits high power on the other or one of the others. In this way, when one of the antennas emits high power on a limited number of sub-carriers according to the previously described technique of increasing the range, the released subcarriers can be used for transmission by one or more other antennas for transmissions to groups of client stations not requiring high transmission power.

Ce mécanisme est illustré par les Fig. 5a et 5b. Ces figures illustrent l'évolution au cours du temps de la densité spectrale de puissance (DSP) du signal envoyé et de la puissance d'émission moyenne des signaux envoyés sur les deux antennes de l'exemple de réalisation de l'invention. La Fig. 5a illustre le signal du premier sous-secteur tandis que la Fig. 5b illustre le signal du second sous-secteur. Ces deux signaux et donc les deux figures sont à lire de manière synchrone sur une même échelle de temps. Sur ces figures sont représentées dans la partie haute de la figure l'utilisation de la bande de fréquence et la puissance d'émission de la partie utilisée de la bande. On voit à la Fig. 5a que, dans un premier temps, on émet à destination du groupe a du sous-secteur 1 en utilisant ¾ de la bande de fréquence avec une puissance d'émission basse. Ensuite, dans un deuxième temps, on émet à destination du groupe b du sous-secteur 1 en utilisant ¾ de la bande de fréquence avec cette fois une puissance d'émission plus élevée correspondant à la puissance moyenne maximale possible. Ensuite, dans un troisième temps, on émet à destination du groupe c du sous-secteur 1 en utilisant seulement un quart de la bande de fréquence avec cette fois une puissance d'émission maximum correspondant par contre toujours à la même puissance moyenne maximale possible pour l'antenne I.This mechanism is illustrated by the Fig. 5a and 5b . These figures illustrate the evolution over time of the power spectral density (DSP) of the signal sent and the average transmission power of the signals sent on the two antennas of the embodiment of the invention. The Fig. 5a illustrates the signal of the first sub-sector while the Fig. 5b illustrates the signal of the second sub-sector. These two signals and therefore the two figures are to be read synchronously on the same time scale. In these figures are shown in the upper part of the figure the use of the frequency band and the transmission power of the used part of the band. We see at the Fig. 5a that, in a first step, it is transmitted to the group a of sub-sector 1 by using ¾ of the frequency band with a low transmission power. Then, in a second step, we send to the group b subsector 1 using ¾ of the frequency band with this time a higher transmission power corresponding to the maximum possible average power. Then, in a third step, it emits to the group c of subsector 1 using only a quarter of the frequency band with this time a maximum transmission power corresponding against always the same average power possible maximum for the antenna I.

De manière synchrone, sur la deuxième antenne, pendant que le sous-secteur 1 émet à puissance faible sur le groupe a le reste de la bande passante, le quart restant est utilisé à pleine puissance pour l'émission vers le groupe c du sous-secteur 2. Pendant que le sous-secteur 1 émet à puissance forte sur le groupe b le reste de la bande passante, le quart restant est utilisé toujours à pleine puissance pour l'émission vers le groupe c du sous-secteur 2. Dans un second temps, c'est le sous-secteur 1 qui utilise la technique d'augmentation de puissance à destination du groupe c tandis que le sous-secteur 2 envoie des données sur le reste du spectre au groupe b puis dans un second temps à puissance réduite au groupe a. On voit que de cette manière, il est possible d'émettre à pleine puissance sur une fraction de la bande de fréquence pour atteindre des stations clientes distantes, le groupe c, sur une des antennes tout en utilisant la fraction de bande de fréquence restante pour une émission à destination de stations clientes plus proches. Cette méthode permet, pour une puissance d'émission donnée, d'augmenter la portée du système tout en garantissant une pleine utilisation de la bande de fréquence et donc de la ressource radio du canal de communication alloué.Synchronously, on the second antenna, while sub-sector 1 is transmitting at low power on group a the rest of the bandwidth, the remaining quarter is used at full power for transmission to group c of the sub-sector. sector 2. While sub-sector 1 transmits the remaining bandwidth at high power on group b, the remaining quarter is always used at full power for transmission to subsector group 2. In a second time, it is sub-sector 1 that uses the power increase technique for group c while subsector 2 sends data on the rest of the spectrum to group b and then in a second time to power reduced to group a. It can be seen that in this way, it is possible to transmit at full power on a fraction of the frequency band to reach remote client stations, the group c, on one of the antennas while using the remaining frequency band fraction for a broadcast to closer client stations. This method makes it possible, for a given transmission power, to increase the range of the system while ensuring full use of the frequency band and therefore the radio resource of the allocated communication channel.

La Fig. 6 illustre l'architecture de la station de base pour un secteur selon un exemple de réalisation de l'invention. Cet exemple reste dans le cadre d'une implémentation à base de deux sous-secteurs et deux antennes, mais elle se généralise de manière immédiate à un nombre plus important de sous-secteurs et d'antennes. On y voit l'émetteur-récepteur numérique composé d'une couche MAC («Médium Access Control» en anglais) qui accède à la base de données 6.1 contenant les informations sur les appartenances aux différents groupes des différentes stations clientes. Au sein de cette couche MAC, les données à transmettre sont donc regroupées en fonction des groupes destinataires. C'est également cette couche 6.2 qui gère l'allocation des sous-porteuses aux différents sous-secteurs. Elle gère aussi les allocations de puissance entre les différents sous-secteurs. Les données sont réparties en fonction du groupe destinataire en différentes rafales (« burst » en anglais) de données réparties au sein du canal de communication. Les données ainsi organisées sont envoyées à un module 6.3 chargé de calculer les codes de redondances et de convertir les données en symboles de transmission. Ces symboles sont alors, en fonction de leur appartenance aux rafales de données, répartis entre plusieurs, ici deux, modules de transformée de Fourier inverse 6.4 et 6.5 pour générer le signal en bande de base en vue de sa transmission au module RF. Préalablement à l'application des transformées de Fourier inverse, une multiplication par un coefficient permet un premier ajustement de la puissance du signal qui va être généré pour chaque sortie. Ces paramètres, ici w1 et w2, sont calculés par le module MAC 6.2. Ces signaux sont alors émis en direction des modules RF et transposés en fréquence pour correspondre au canal de communication alloué par les modules de transposition 6.6 et 6.7. Un dernier ajustement des puissances des signaux est effectué par des amplificateurs 6.8 et 6.9 commandés par des paramètres p1 et p2 également calculés par la couche MAC 6.2. Les signaux correspondant à chaque sous-secteur sont alors émis par l'antenne correspondante 6.10 ou 6.11.The Fig. 6 illustrates the architecture of the base station for a sector according to an exemplary embodiment of the invention. This example remains in the context of an implementation based on two sub-sectors and two antennas, but it is spreading immediately to a larger number of sub-sectors and antennas. It shows the digital transceiver composed of a MAC layer ("Medium Access Control" in English) which accesses the database 6.1 containing information on the membership of different groups of different client stations. Within this MAC layer, the data to be transmitted are therefore grouped according to the recipient groups. It is also this layer 6.2 which manages the allocation of the sub-carriers to the different sub-sectors. It also manages power allocations between different sub-sectors. The data is divided according to the destination group in different bursts ("burst" in English) of data distributed within the communication channel. The data thus organized are sent to a module 6.3 responsible for calculating the redundancy codes and converting the data into transmission symbols. These symbols are then, according to their belonging to the data bursts, distributed among several, here two, inverse Fourier transform modules 6.4 and 6.5 to generate the baseband signal for transmission to the RF module. Prior to the application of the inverse Fourier transforms, a multiplication by a coefficient allows a first adjustment of the power of the signal that will be generated for each output. These parameters, here w1 and w2, are calculated by the MAC module 6.2. These signals are then transmitted towards the RF modules and transposed in frequency to correspond to the communication channel allocated by the transposition modules 6.6 and 6.7. A final adjustment of the signal powers is performed by amplifiers 6.8 and 6.9 controlled by parameters p1 and p2 also calculated by the MAC layer 6.2. The signals corresponding to each sub-sector are then emitted by the corresponding antenna 6.10 or 6.11.

Dans le cas où l'invention est implémentée dans le cadre de la norme IEEE 802.16, la norme prévoit les fonctionnalités nécessaires à l'implémentation de l'invention. La Fig. 7 illustre schématiquement la trame WIMAX en TDD (« Time Division Duplex » en anglais) comprenant deux phases. Dans une première phase dite descendante, DL (« Down Link » en anglais), de communication de la station de base vers les stations clientes, la communication démarre par l'émission d'un préambule 7.1 transmis sur la totalité du canal et des informations sur l'allocation de la ressource radio pour cette phase descendante. On y trouve également l'allocation des données 7.2 de la phase montante, UL (« Up Link » en anglais) puis les différentes rafales de données émises 7.3. Après un temps de garde destiné à absorber les différences de délai de propagation des différentes stations clientes, le canal est occupé par les rafales de données montantes 7.4. La norme IEEE802.16 supporte la possibilité d'envoyer sur la voie descendante des rafales de données dans un mode dédié (zone STC), dans lequel les stations clientes concernées n'utilisent que les pilotes nécessaires pour décoder leurs rafales et non tous les pilotes émis par la station de base. Dans ce cadre, la découpe des données en fonction des différents groupes des différents sous-secteurs utilise ce découpage en rafales et va allouer les différentes rafales aux différents sous-secteurs et groupes de stations clientes. La puissance d'émission des différentes rafales peut être ajustée grâce au champ « power boosting » prévu dans la structure DL MAP IE servant à décrire l'allocation des ressources radio dans la norme.In the case where the invention is implemented within the framework of the IEEE 802.16 standard, the standard provides the functionalities necessary for the implementation of the invention. The Fig. 7 schematically illustrates the WIMAX frame in TDD ("Time Division Duplex") comprising two phases. In a first so-called downlink phase, DL ("Down Link" in English), of communication from the base station to the client stations, the communication starts with the transmission of a preamble 7.1 transmitted over the entire channel and information on the allocation of the resource radio for this downward phase. There is also the data allocation 7.2 of the rising phase, UL ("Up Link" in English) and the various data bursts issued 7.3. After a guard time to absorb the propagation delay differences of the different client stations, the channel is occupied by the data bursts 7.4. The IEEE802.16 standard supports the ability to send data bursts to the downstream channel in a dedicated mode (STC zone), in which the client stations concerned only use the necessary drivers to decode their bursts and not all the pilots. issued by the base station. In this context, the cutting of the data according to the different groups of the different sub-sectors uses this burst division and will allocate the different bursts to the different sub-sectors and groups of client stations. The transmission power of the different bursts can be adjusted by means of the "power boosting" field provided in the DL MAP IE structure used to describe the allocation of radio resources in the standard.

Les données de chaque rafale sont envoyées selon un mode physique particulier. Ce mode physique est défini par la modulation utilisée contenant plus ou moins de symboles et par le choix du code correcteur d'erreur choisi. Plus la qualité de la transmission est bonne, plus il est possible de choisir une modulation utilisant un grand nombre de symboles et un code correcteur apportant peu de redondance. Au contraire, quand la qualité de transmission est moins bonne, il est nécessaire d'utiliser un mode physique plus robuste constitué d'une modulation utilisant un nombre moindre de symboles et un code correcteur apportant plus de redondance. L'invention permet de transmettre ponctuellement avec une plus grande puissance d'émission pour combattre efficacement le niveau de bruit et d'interférence perçu par les stations clientes. Elle permet ainsi d'utiliser des modes physiques moins robustes augmentant d'autant la bande passante du canal de transmission. L'invention permet également de diminuer statistiquement l'énergie émise dans chaque sous-secteur, ce qui réduit significativement le niveau d'interférence pour les cellules voisines.The data of each burst is sent in a particular physical mode. This physical mode is defined by the modulation used containing more or fewer symbols and by the choice of the error correcting code chosen. The higher the quality of the transmission, the more it is possible to choose a modulation using a large number of symbols and a correction code providing little redundancy. On the contrary, when the transmission quality is less good, it is necessary to use a more robust physical mode consisting of a modulation using a lesser number of symbols and a corrector code providing more redundancy. The invention makes it possible to transmit punctually with a greater power of emission to effectively combat the level of noise and interference perceived by the client stations. It thus makes it possible to use less robust physical modes increasing the bandwidth of the transmission channel by the same amount. The invention also makes it possible to statistically reduce the energy emitted in each sub-sector, which significantly reduces the level of interference for neighboring cells.

L'homme du métier comprendra que l'invention ici décrite dans le cadre du système de transmission cellulaire WIMAX pourra être utilisée dans tout type de réseau de communication entre un point d'accès et des stations clientes basé sur une transmission partageant la ressource radio, d'une part, sur une base temporelle et, d'autre part, sur une base fréquentielle. En particulier, il est possible d'implémenter l'invention dans un système où le partage du canal est basé sur un partage par code CDMA (« Code Division Multiple Access » en anglais). Dans ce cas, les différents signaux codés avec leurs codes respectifs sont envoyés via les différentes antennes avec une puissance adaptée selon l'invention. Elle permet d'améliorer l'utilisation du canal de transmission en multipliant le nombre d'antennes utilisées pour couvrir un secteur sans nécessiter la multiplication des modules émetteurs-récepteurs correspondants. Elle permet d'augmenter la portée du système tout en garantissant une très bonne utilisation de la ressource radio du canal de transmission et une bonne bande passante.Those skilled in the art will understand that the invention described herein as part of the WIMAX cellular transmission system may be used in any type of communication network between an access point and client stations based on a transmission sharing the radio resource, on the one hand, on a time basis and, on the other hand, on a frequency basis. In particular, it is possible to implement the invention in a system where the sharing of the channel is based on code division multiple access (CDMA). In this case, the different Coded signals with their respective codes are sent via the different antennas with a suitable power according to the invention. It makes it possible to improve the use of the transmission channel by multiplying the number of antennas used to cover a sector without requiring the multiplication of the corresponding transceiver modules. It makes it possible to increase the range of the system while guaranteeing a very good use of the radio resource of the transmission channel and a good bandwidth.

Claims (12)

  1. Method for transmitting data within a multiple access communication system using a transmission channel defined by a frequency band comprising a plurality of sub-carriers and allocated to the transmission of signals between a base station, comprising a plurality of antennas, and a set of client stations within a zone called a sector, the set of client stations being divided into groups of client stations as a function of an emission power necessary to establish a communication with the base station, characterized in that it comprises the following steps:
    - a step of defining a plurality of sub-sectors, each sub-sector corresponding to an antenna,
    - a step of allocating sub-carriers of the frequency band of the transmission channel to the sub-sectors, the allocation of the sub-carriers between the sub-sectors being done in a dynamic manner over time as a function of the groups of client stations, and,
    - for each antenna, a step of emitting signals, the emission being done on the sub-carrier or sub-carriers allocated to the sub-sector corresponding to the said antenna,
    the signals corresponding to the communications being distributed over time in such a way that, at a given instant, the signals emitted by an antenna corresponding to a sub-sector are destined for client stations of a group of client stations, the emission power of the signals emitted by each antenna being modulated in a synchronized manner between the antennas as a function of time and of the groups of recipient client stations, when an antenna emits at high power on some sub-carriers, the other sub-carriers being used for the emission by one or more other antennas for emissions destined for groups of client stations not requiring a high emission power.
  2. Method according to Claim 1 where the step of modulating the emission power of the signals corresponding to each sub-sector comprises a step of multiplication by a coefficient (w1, w2) of the data to be emitted prior to the generation of the baseband signal by inverse Fourier transform within the emitter-receiver.
  3. Method according to Claim 2 where the step of modulating the emission power of the signals corresponding to each sub-sector comprises a step of parametrized amplification (p1, p2) of the signals to be emitted.
  4. Method according to one of Claims 1 to 3 where the sharing of the bandwidth is done on the basis of frequency sub-bands.
  5. Method according to Claim 4 where the system being based on orthogonal frequency division multiple access, OFDM, the sharing unit is the sub-carrier of the system.
  6. Method according to one of Claims 1 to 3 where the sharing of the bandwidth is done on the basis of code division in a system based on code division multiple access, CDMA.
  7. Device for transmitting data within a multiple access communication system using a transmission channel defined by a frequency band comprising a plurality of sub-carriers and allocated to the transmission of signals between a base station comprising a plurality of antennas and a set of client stations within a zone called a sector, characterized in that it comprises:
    - means for defining a plurality of sub-sectors, each sub-sector corresponding to an antenna,
    - means for allocating sub-carriers of the frequency band of the transmission channel to the various sub-sectors, the allocation of the sub-carriers between the sub-sectors being done in a dynamic manner over time as a function of the groups of client stations, and,
    - means for emitting the signals for each antenna, the emission for an antenna being done on one of the sub-carriers allocated to the sub-sector corresponding to the antenna,
    - means for dividing the set of client stations into groups of client stations as a function of the emission power necessary to establish a communication with the base station,
    - means for distributing the signals corresponding to the communications over time in such a way that, at a given instant, the signals emitted by an antenna corresponding to a sub-sector are destined for client stations of a group of client stations,
    - means for modulating the emission power of the signals emitted by each antenna, the modulation being done in a synchronized manner between the antennas as a function of time and of the groups of recipient stations, and, when an antenna emits at high power on some sub-carriers, the other sub-carriers being used for the emission by one or more other antennas for emissions destined for groups of client stations not requiring a high emission power.
  8. Device according to Claim 7 where the means for modulating the emission power of the various signals comprise means for multiplying by a scalar (w1, w2) the data to be emitted prior to the generation of the baseband signal by inverse Fourier transform within the emitter-receiver.
  9. Device according to Claim 7 where the means for modulating the emission power of the various signals comprise means for parametrized amplification (p1, p2) of the signals to be emitted.
  10. Device according to one of Claims 7 to 9 where the sharing of the bandwidth is done on the basis of frequency sub-bands.
  11. Device according to Claim 10 where the system being based on orthogonal frequency division multiple access, OFDM, the sharing unit is the sub-carrier of the system.
  12. Device according to one of Claims 7 to 9 where the sharing of the bandwidth is done on the basis of code division in a system based on code division multiple access, CDMA.
EP07024609.5A 2006-12-20 2007-12-19 Method and arrangement for dynamic management of sub-sectors in a cellular communication system Active EP1937011B1 (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
FR0611187A FR2910774B1 (en) 2006-12-20 2006-12-20 METHOD AND DEVICE FOR DYNAMIC MANAGEMENT OF SUB-SECTORS IN A CELLULAR COMMUNICATION SYSTEM

Publications (2)

Publication Number Publication Date
EP1937011A1 EP1937011A1 (en) 2008-06-25
EP1937011B1 true EP1937011B1 (en) 2017-08-23

Family

ID=38185439

Family Applications (1)

Application Number Title Priority Date Filing Date
EP07024609.5A Active EP1937011B1 (en) 2006-12-20 2007-12-19 Method and arrangement for dynamic management of sub-sectors in a cellular communication system

Country Status (3)

Country Link
EP (1) EP1937011B1 (en)
ES (1) ES2648793T3 (en)
FR (1) FR2910774B1 (en)

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2693794B1 (en) * 2012-08-02 2018-12-19 Alcatel Lucent Load distribution dependent dynamic adaptation of vertical sectors in a cell
CN117915350A (en) * 2022-10-18 2024-04-19 中兴通讯股份有限公司 Base station

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1996037082A1 (en) * 1995-05-18 1996-11-21 Nokia Telecommunications Oy Increasing capacity in a cellular mobile telephone network

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6151310A (en) * 1994-03-24 2000-11-21 Ericsson Inc. Dividable transmit antenna array for a cellular base station and associated method
US5758090A (en) * 1995-09-22 1998-05-26 Airnet Communications, Inc. Frequency reuse planning for CDMA cellular communication system by grouping of available carrier frequencies and power control based on the distance from base station

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1996037082A1 (en) * 1995-05-18 1996-11-21 Nokia Telecommunications Oy Increasing capacity in a cellular mobile telephone network

Also Published As

Publication number Publication date
FR2910774B1 (en) 2009-03-06
EP1937011A1 (en) 2008-06-25
ES2648793T3 (en) 2018-01-08
FR2910774A1 (en) 2008-06-27

Similar Documents

Publication Publication Date Title
US10230452B2 (en) Terrestrial based air-to-ground communications system and related methods
US10349332B2 (en) Network communication using selected resources
EP3461030B1 (en) Method for allocating frequency resources for a satellite telecommunication system
KR101260097B1 (en) Apparatus and method for broadcast superposition and cancellation in a multi-carrier wireless network
AU2005253596B2 (en) Wireless communication system with configurable cyclic prefix length
TWI383604B (en) Constrained hopping in wireless communication systems
EP2302822B1 (en) Telecommunication system with a multibeam satellite and method of beams formation
US20060193373A1 (en) Highly bandwidth-efficient communications
JP5167212B2 (en) Multi-carrier communication method
JP2002515203A (en) Use of orthogonal waveforms to allow multiple transmitters to share one CDM channel
US8130868B2 (en) Radio communication apparatus, radio communication method and program storage medium
WO2022198349A1 (en) Method, apparatus, and medium for modulation of waveform in fractional domain for integrated sensing and communication
WO2003058906A2 (en) Method of managing communications in a network and the corresponding signal, transmitting device and destination terminal
EP1937011B1 (en) Method and arrangement for dynamic management of sub-sectors in a cellular communication system
EP3244547A1 (en) Mimo-fbmc transmitter/receiver with linear precoding implemented in the frequency domain
Xu et al. Identification and practical validation of spectrally efficient non-orthogonal frequency shaping waveform
Garroppo et al. Experimental and simulation analysis of a WiMAX system in an emergency marine scenario
Ghosh Performance evaluation of different coding and modulation scheme in LTE using different bandwidth and correlation levels
Zhang et al. On the Uplink Performance of Multi-User MC-CDMA Satellite-Terrestrial Deliveries
EP1425864A1 (en) Method and system for data broadcast from a satellite
WO2006069826A1 (en) Method for transmitting multicarrier signals in a planned macro-diversity multicellular network, corresponding network, signal, reception method and device
Kim et al. Satellite frequency reuse method for complementary ground components in an integrated mss system
Mustafa et al. Adjacent Channel Interference Reduction in OFDM Systems
FR2823623A1 (en) Bidirectional digital transmission system having multiple carrier signals base station/terminal passed with estimation step transfer function analysing down signal received/delivering estimation information/carrying out predistortion.
Qu et al. A Study of Irregular Repetition Slotted ALOHA Over LEO Satellite Channel with Capture Effect

Legal Events

Date Code Title Description
PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

Free format text: ORIGINAL CODE: 0009012

AK Designated contracting states

Kind code of ref document: A1

Designated state(s): AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HU IE IS IT LI LT LU LV MC MT NL PL PT RO SE SI SK TR

AX Request for extension of the european patent

Extension state: AL BA HR MK RS

17P Request for examination filed

Effective date: 20081024

17Q First examination report despatched

Effective date: 20081127

AKX Designation fees paid

Designated state(s): DE ES FR GB IT

RAP1 Party data changed (applicant data changed or rights of an application transferred)

Owner name: SAGEM COMMUNICATIONS SAS

RAP1 Party data changed (applicant data changed or rights of an application transferred)

Owner name: SAGEM COMMUNICATIONS

RAP1 Party data changed (applicant data changed or rights of an application transferred)

Owner name: SAGEM COMMUNICATIONS SAS

RAP1 Party data changed (applicant data changed or rights of an application transferred)

Owner name: SAGEMCOM ENERGY & TELECOM

RAP1 Party data changed (applicant data changed or rights of an application transferred)

Owner name: SAGEMCOM ENERGY & TELECOM SAS

RAP1 Party data changed (applicant data changed or rights of an application transferred)

Owner name: SAGEMCOM BROADBAND SAS

REG Reference to a national code

Ref country code: DE

Ref legal event code: R079

Ref document number: 602007052068

Country of ref document: DE

Free format text: PREVIOUS MAIN CLASS: H04Q0007360000

Ipc: H04W0016300000

GRAP Despatch of communication of intention to grant a patent

Free format text: ORIGINAL CODE: EPIDOSNIGR1

RIC1 Information provided on ipc code assigned before grant

Ipc: H04W 52/42 20090101ALN20170118BHEP

Ipc: H04W 16/10 20090101ALN20170118BHEP

Ipc: H04W 16/30 20090101AFI20170118BHEP

INTG Intention to grant announced

Effective date: 20170202

GRAS Grant fee paid

Free format text: ORIGINAL CODE: EPIDOSNIGR3

GRAA (expected) grant

Free format text: ORIGINAL CODE: 0009210

AK Designated contracting states

Kind code of ref document: B1

Designated state(s): DE ES FR GB IT

REG Reference to a national code

Ref country code: GB

Ref legal event code: FG4D

Free format text: NOT ENGLISH

REG Reference to a national code

Ref country code: DE

Ref legal event code: R096

Ref document number: 602007052068

Country of ref document: DE

REG Reference to a national code

Ref country code: FR

Ref legal event code: PLFP

Year of fee payment: 11

REG Reference to a national code

Ref country code: ES

Ref legal event code: FG2A

Ref document number: 2648793

Country of ref document: ES

Kind code of ref document: T3

Effective date: 20180108

REG Reference to a national code

Ref country code: DE

Ref legal event code: R097

Ref document number: 602007052068

Country of ref document: DE

PLBE No opposition filed within time limit

Free format text: ORIGINAL CODE: 0009261

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: NO OPPOSITION FILED WITHIN TIME LIMIT

26N No opposition filed

Effective date: 20180524

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: IT

Payment date: 20221122

Year of fee payment: 16

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: GB

Payment date: 20231124

Year of fee payment: 17

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: FR

Payment date: 20231122

Year of fee payment: 17

Ref country code: DE

Payment date: 20231121

Year of fee payment: 17

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: ES

Payment date: 20240102

Year of fee payment: 17